Do Dietary Supplements Work? Are They Safe?
Seven things doctors want you to know before you take them
Seven things doctors want you to know before you take them
Dietary supplements — including vitamins, minerals, herbs and fish oils — are widely used to support health and wellness. Many people take them hoping to boost their immune system, improve energy or support overall health.
But do dietary supplements actually work? Are they safe for everyone?
With thousands of dietary supplements available without a prescription, it can be hard to know which products are effective, necessary or even safe. Marketing claims can be confusing and don’t always reflect strong scientific evidence.
Before adding a supplement to your routine, it’s important to know the benefits and risks. You should also understand how these products are regulated. Some supplements can help with nutrient gaps or support health needs. However, others may interact with medications, cause side effects or be harmful in high doses.
“Not everyone needs supplements. But if you’re thinking of taking them, do your homework,” says Immanuel Hausig, DO, a family medicine physician at Scripps Coastal Medical Center Carlsbad. “Learn how safe and effective they are first.”
“Your doctor can tell you what conditions supplements can help with and which ones, if any, are right for you,” Dr. Hausig says.
Here are seven evidence-based facts to know about supplements before taking them:
1. Dietary supplements are not regulated like drugs
The U.S. Food and Drug Administration (FDA) regulates dietary supplements, but not in the same way it regulates prescription or over-the-counter drugs. Supplements are regulated as foods, not as treatments for disease.
The FDA does not check the safety or effectiveness of dietary supplements before they are sold. Instead, supplement makers must ensure their products are safe and accurately labeled.
Once supplements are on the market, the FDA monitors safety and can remove products found to be unsafe or take action against false or misleading claims.
2. Supplement makers can make limited health claims
By law, dietary supplement companies cannot claim their product treats, prevents or cures diseases. Only FDA-approved drugs can make those claims.
However, supplement labels may include certain types of statements about health. These fall into three main categories:
- Authorized health claims are approved by the FDA and supported by strong scientific evidence. For example, getting enough calcium as part of a healthy diet may reduce the risk of osteoporosis.
- Qualified health claims link a nutrient to disease risk but are based on more limited evidence and must include qualifying language or a disclaimer.
- Structure/function claims describe how a nutrient supports normal body structure or function, such as “supports heart health” or “supports immune health.” These claims do not mention diseases and must state that the claim has not been evaluated by the FDA.
Understanding these differences can help consumers better evaluate supplement marketing claims and avoid confusing general wellness statements with proven medical benefits.
3. Some supplements can interact with medications or affect medical conditions
Supplements can affect prescription medications or make some health conditions worse. This is especially true when taken in high doses or with other supplements.
Talk to your doctor before taking any supplements. This is important if you take medications, have a chronic condition, are pregnant or are getting ready for surgery.
According to the FDA:
- Vitamin K can reduce the effectiveness of blood thinners.
- St. John’s wort can alter how the body processes many medications.
- Antioxidant supplements may reduce the effectiveness of some cancer treatments.
4. Knowing how to read supplement labels helps ensure safe use
Supplement labels contain important information about ingredients, dosage and safety.
Understanding how to read them can help you choose appropriate products and avoid side effects.
- Serving size: Taking more than recommended can increase health risks.
- Ingredient lists: Help prevent excessive intake from multiple sources.
- Daily value (DV) percentages: Higher amounts are not always better.
5. Supplement claims should not replace medical advice
Claims on labels provide general information and do not guarantee results or replace medical care.
If you’re not sure how to interpret a label or whether a supplement is right for you, talk to your doctor.
6. Supplements can’t replace a healthy diet and are not for everyone
Supplements should never replace a balanced, nutrient-rich diet. Whole foods provide vitamins, minerals and additional benefits that supplements cannot fully replicate.
“If you’re thinking of taking a dietary supplement, ask yourself if you can get these nutrients from the foods you’re eating,” Dr. Hausig says. “Most of the time you can. And many foods are fortified with added nutrients.”
That said, some people have nutritional deficiencies due to health conditions or life stages. Supplements can help fill these gaps.
For example:
- Folic acid is very important before and during early pregnancy. While folate is found in foods, many women do not get enough. Taking 400 to 800 micrograms each day helps prevent neural tube defects that can happen early in pregnancy.
- Vitamin D deficiency is common. It often affects people with limited sun exposure, darker skin, older age, obesity or digestive issues. In these cases, supplements can help restore healthy levels when diet and sunlight are not enough.
Dr. Hausig cautions against taking more supplements than necessary.
Taking too much vitamin A, for example, can cause headaches and liver damage. It can also weaken bones and cause birth defects.
While some people with absorption issues or severe deficiencies may need supplements, most get enough vitamin A from food and should avoid high-dose products unless advised by a doctor.
7. Use reliable resources to check quality of supplements
Along with advice from your doctor, trusted and non-commercial resources can help you make good decisions. These include:
- The U.S. Office of Dietary Supplements for evidence-based supplement information
- The U.S. Pharmacopeia (USP) Verified Mark to check that a supplement has the listed ingredients at the stated potency, is free from harmful contaminants, dissolves well and is made according to good manufacturing practices
Make supplements a shared decision with your doctor
Before taking any supplement, consider your health, diet, medications and personal risks. What works for one person may not work for another. It could even be harmful.
A quick chat with your doctor can help you decide if a supplement is right for you. They can also advise you on how much to take and for how long.
“It’s essential to approach dietary supplements with a balanced perspective, understanding their benefits and limitations,” Dr. Hausig says. “Your doctor can guide you based on your individual health needs.”
If you’re considering a supplement, bring the product label or a list of medications you take to your next appointment so your doctor can help you make informed, safe choices.